Electromagnet



Feb. 13, 1962 L. L. WEBER ELECTROMAGNET Filed Jan. 6, 1960 LEO L.WEBER av W5. W

AGENT .United States Patent 3,021,455 ELECTROMAGNET Leo L. Weber, Logansport, lnd., assignor to Essex Wire Corporation, Fort Wayne, Ind., a corporation of Michigan Filed Jan. 6, 1960, Ser. No. 817

3 Claims. (Cl. 317-191) 3,021,455 Patented Feb. 13, 1962 "ice f carried out in other ways without departing from the but generally the bobbin is confined between two or more 1 individual parts of the frame which are bolted or riveted together. I i

It is an object of this invention to provide an improved arrangement for securing together the frame and coil bobbin of an electromagnet.

Another object of this invention is to provide an improved electromagnet construction in which a frame consisting of only a single member is easily assembled and firmly secured upon a coil bobbin without the use of 7 resilient sheet metal is sprung over and embraces the end flanges of a bobbin having a hollow barrel upon which a coil is wound. The legs of the frame and the flanges of the bobbin have interlocking means for holding the frame upon the bobbin in a predetermined oriented position so that a pole piece formed by one of the legs is disposed in proper alignment with a core armature movable within the barrel of the bobbin. In accordance with another feature of the invention, the pole piece is defined by the end of a leg which is formed with a configuration corresponding to the configuration of a portion of the outer surface of the armature. According to a further feature of the invention, the bobbin may be formed of insulating material and carries a fixed spark electrode engaged by a movable electrode attached to the armature.

Other objects and features of the invention will be apparent from reference to the following description and accompanying drawing in which:

FIG. 1 is a top plan view of a spark ignition device embodying the present invention;

FIG. 2 is a sectional view taken substantially along the line 22 of FIG. 1;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a bottom plan view of the ignition device;

FIG. 5 is an oblique view of the frame of the ignition device; and

FIG. 6 is an oblique sectional view of the bobbin of the ignition device. a

The spark ignition device illustrated in the drawing and hereinafter described constitutes a preferred embodiment of the invention which has particular utility as an igniter for a gas burner. However, it should be understood that the following description and the accompanying drawing are illustrative only and are not to be interscope ,of the invention as claimed in the appended claims.

Referring to the drawing, there is shown a spark ignition device which has a coil winding 10 of insulated wire on a bobbin 11 formed of insulatingmaterial. Bobbin 11 comprises flanges 12 and 13 preferably formed integrally as by molding with a barrel 14 which is provided with a central opening 15. The opening 15 is nearly closed at one end by a disclike inward flange 16 formed integrally with flange 13. Sprung over and secured on the flanges 12 and 13 is a generally U-shaped frame 17 formed from suitable resilient ferrous sheet metal and having an intermediate connecting portion 18 and two end portions or legs 19 and 20. Legs 19 and 20 are spaced apart a distance substantially equal to the spacing between the (interfaces of the flanges 12 and 13 and are disposed to bear against the flanges. The leg 19 overlying flange 12 is provided with a hole 21 in which is seated a projecting lug 22 integrally formed on flange 12. The other leg 20 overlies flange 13 and has a bent extension 23 engaging the outer peripheral surface of flange 13. Flange 13 is provided with two pins 24 between which leg 20 is positioned to ensure the desired angular. relationship between the frame 17 and the bobbin 11. ,The notched end 25 of leg 19 has an arcuate edge 26. of slightly greater radius than opening 15 and is axially alignedtherewith to form a pole piece.

An armature 27 of suitable ferrous metal is slidable within opening 15 and has a reduced diameter end 28 which is movable toward the inward flange 16 against the force of a coilspring 29 confined between armature 27 and the inward flange 16. The other end of armature 27 projects from opening 15 with a slight spacing be,- tween armature 27 and edge 26 of leg 19 and has attached thereto an electrode rod 30 of conductive metal.

The rod 30 has welded to its free end a movable contact 31 normally urged by spring 29 into engagement with a fixed contact 32 defined by the coiled end of a fixed electrode rod 33. The other end of rod 33 is suitably secured as by welding to a terminal bracket 34 which is attached to flange 12 of the bobbin 11. Also fastened to flange 12 are a terminal member 35 and a flag terminal 36 to which the ends 37 and 38 respectively of coil windreception of guide projection 43 in slot 42. Guide projection 43 comprises an integral extension of a raised ridge 44 on flange 12 which serves to isolate mounting bracket 45 from the adjacent portions of the igniting device. An additional raised ridge 46 is provided with V a portion disposed between terminal member 35 and terminal 36 and cooperates with ridge 44 to provide a channel 47 in which leg 19 is positioned.

From the foregoing description of the ignition device, it will be apparent that all the elements except the frame 17 may be assembled upon the bobbin 11 in a conventional manner. The frame 17 is merely sprung in posi tion on the bobbin 11 and retained thereon without the use of any additional fastening means. The leg 19 is inserted in channel 47 of flange 12 with hole 21 positionedabove lug 22. The leg 20 is then tensioned outwardly and forced across flange 13 between pins 24 until extension 23 snaps over the edge of flange 13. .As a a consequence of this snap engagement, the frame 17 and bobbin 11 are maintained in assembled relation.

When the terminal bracket 34 and terminal member 35 are connected to a suitable source of electric power, winding will be energized through a circuit comprising terminal bracket 34, fixed electrode rod 33, fixed contact 32, movable contact 31, electrode rod 39, armature 27, terminal 40, conductor 39, terminal 36, winding 10 and terminal member 35. The magnetic flux generated when winding 10 is energized will flow in a magnetic circuit comprising frame 17 and armature 27. When the flux builds up to a suflicient value, the reduced diameter end 28 of armature 27 will move against the force of spring 29 toward inward flange 16 to reduce the air gap between arrnature 27 and leg 20. As the armature moves, it separates contact 31 from contact 32 of the fixed electrode rod 33, thereby producing a spark between the contacts. This interrupts the circuit to the winding 11 and the armature 27 will be returned to its original position by spring 29. Contact 31 will again engage contact 32 and the foregoing operation will be repeated as long as power is supplied to the ignition device.

What is claimed is:

1. In an electromagnet of the type having a coil wound upon a bobbin of nonmagnetic material, said bobbin having a hollow barrel and two end flanges, a core armature movable in said barrel and projecting from one end thereof through an opening in one of said flanges, said arrnature being adapted to have its inner end attracted further into the bobbin upon energization of the coil, and a frame of magnetic material extending between the ends of said barrel; the improvement wherein said frame comprises a generally U-shaped member formed of resilient sheet metal and adapted to be sprung over said bobbin in snapping engagement therewith, said frame member comprising a pair of legs spaced apart a distance substantially equal to the spacing between the outer faces of said flanges, one of said legs overlying the outer face of said one flange, the other of said legs overlying the outer face of the other of said flanges, said legs being connected by a connecting portion extending lengthwise along the outside of said bobbin; the end of said one leg being shaped to define a pole piece spaced slightly from said projecting end of said armature and having a configuration corresponding to the configuration of a portion of the outer surface of said projecting end of said armature, the outer face of said one flange having a projecting lug spaced from said opening in said one flange, said one leg being provided with a hole receiving said lug to position said pole piece in respect to said armature, and the end of said other leg being provided with a bent extension disposed in clasping engagement with the edge of said other flange and cooperating with means including said hole in said one leg and said lug for efiecting quick attachment of said frame member to said bobbin and for retaining the same in assembled relation.

2. In an electromagnet, the combination comprising: a bobbin or non-magnetic material having a barrel and two end flanges; an axial passage Within said barrel that extends through a first one of said flanges; an armature slidably positioned in said passage and having a portion extending outwardly from said one flange; a coil encircling said barrel for operating said armature; a generally lJ-shaped frame formed of a single strip of resilient magnetic sheet metal and comprising a pair of substantially parallel and aligned legs interconnected at adjacent ends and spaced apart a distance substantially equal to the spacing between the outer faces of said flanges; the portion of said frame connecting said legs extending lengthwise along the outside of said bobbin; a first one of said legs lying against the outer face of said first flange; the second one of said legs lying against the outer face of the second one of said flanges; the outer faces of said flanges having locating projections positioned at opposite edgesof said legs to locate said legs in predetermined positions in respect to said flanges and to prevent turning of said frame relative to said bobbin; the free end of said first leg being shaped to define a pole piece in alignment with said armature; interlocking means on the facing surfaces of said first flange and said first leg comprising an opening provided in one of said surfaces and a lug projecting from the other of said surfaces into said opening to locate said pole piece in a predetermined posi-' tion relative to said armature; said second leg extending completely across said second flange and having its free end bent toward said first leg to form an extension engaging the peripheral edge of said second flange in clasping relation and cooperating with said interlocking means for effecting quick attachment of said frame to said bobbin and retaining the same in assembled relation.

3. In an electrom agnet as defined in claim 2, wherein said passage extends substantially completely through said barrel; and the inner end of said armature is movable in said passage to a position closely adjacent said second leg to provide for direct magnetic attraction of said inner end of said armature to said second leg upon energization of said coil.

Gruhlke Mar. 10, 1925 Eck Feb. 3, 1953 

